Chapter 5: Nutrition in Humans

Ingestion

The intake of food into the mouth.

Physical digestion

The breakdown of food into smaller pieces without chemical changes.

Chemical digestion

The breakdown of large food molecules into small, soluble molecules by enzymes.

Absorption

The movement of digested nutrients and mineral salts into the bloodstream, and water by osmosis.

Assimilation

The process where absorbed nutrients are transported into cells and used to synthesize new cells/tissues or release energy.

Egestion

The removal of undigested food matter from the body as faeces through the anus.

Peristalsis

Involuntary rhythmic, wave-like contractions of muscles that mix and propel the contents of the alimentary canal.

Emulsification of fats

The physical breakdown of large fat globules into smaller fat droplets.

Bile

A substance produced by the liver that emulsifies fats.

Amylase

An enzyme that digests starch into maltose.

Protease

An enzyme that breaks down proteins/polypeptides into amino acids.

Lipase

An enzyme that digests fats into fatty acids and glycerol.

Gastric juice

A fluid in the stomach containing protease/pepsin and hydrochloric acid.

Intestinal juice

A fluid in the small intestine containing maltase, protease/peptidase, and lipase.

Hepatic portal vein

The vessel that transports absorbed nutrients from the small intestine to the liver.

Detoxification

The conversion of harmful substances in the blood into harmless substances by the liver.

Insulin

A hormone produced by the pancreas that helps regulate blood glucose levels.

Glucagon

A hormone produced by the pancreas that raises blood glucose levels.

Diabetes mellitus

A disease where the body is unable to regulate blood glucose concentration, resulting in persistently higher-than-normal blood glucose.